(a) Field of the Invention
The present invention relates to a method for controlling a shift during a shift of an automatic transmission. More particularly, the present invention relates to a method for controlling a shift during a shift of an automatic transmission that controls to complete an N to N-2 shift and an N-2 to N-3 shift simultaneously such that the shift during a shift is smoothly performed when the N-2 to N-3 shift where one frictional element is released is required to be performed during the N to N-2 shift where another frictional element is released and a further frictional element is engaged.
(b) Description of the Related Art
Generally, an automatic transmission provides convenient driving by achieving automatic shifting to a target shift speed as a consequence of the target shift speed being derived from a predetermined shifting pattern based on a vehicle speed and variation of a throttle opening, and then operational elements being controlled according to a hydraulic duty of the target shift speed.
In a case that the shifting to the target shift speed is performed, an automatic transmission has an off-going element that changes from an engaged state to a released state and an on-coming element that changes from a released state to an engaged state. Releasing an off-going element and engaging an on-coming element is realized by controlling a hydraulic pressure supplied to respective elements.
According to a conventional method for controlling a shift during a shift of an automatic transmission, a following shift begins after completing a previous shift. Therefore, a time needed for completion of a shift may be long and shift feel may be deteriorated.
In addition, there exists another method where the following shift is overlapped with the previous shift, wherein the following shift is completed after completion of the previous shift. However, according to the above method, the previous and following shifts are completed at different times and a double shift may be felt accordingly.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.